Duncan push-in fittings are made from Acetal resin moulded with nickel plated brass insert. It uses NBR (Nitrile) rubber "U" cup for creating a leakproof joint with PU tube when it is inserted into the push in fitting. The PU tube is locked inside the fitting by using S S lock claws with a unique profile to prevent accidental release of PU tube. However, the PU tube can be easily released when required, by pressing down on "release sleeve" with a finger and pulling the tube out without any tool.
Duncan BSPT push-in fittings are pre-coated with Teflon thread sealant while BSPP push-in fittings are provided with face sealing "O" ring to create a leak-proof joint where push-in fitting is fitted on.